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The 4150 has 4 idle mixture screws. Just wondering what the procedure is to get all 4 of these adjusted properly. Thanks for any help

Mike
 

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Mike, really not much different then a carb with only two mixture screws. You want to be sure all 4 screws are within 1/8 turn of each other and it also helps if front and rear throttle plates(idle speed screws) are also opened the same amount. Once engine is warm timing set and a vacum gauge and or tach connected start with each mixture screw 1 1/2 turns out from seated position. You want to go "around" the carb starting with the front mixture screws and make 1/4 turn in or out(depending which way makes engine idle speed up or smooth out) on each mixture till best idle quality and highest rpm and highest vacum reading. You will find it's probally needed to fine adjust the idle speed as you adjust idle mixture since it will increase as the mixture get closer to correct. Most times with holleys once the best idle mixture is found,1/8 additional turn out of each mixture screw may be needed to correct a off idle stumble but this should only be done once you are sure squirter size,accel. pump discharge timeing(pump cam location) are correct. If you find after the mixture adjustment is set the the idle speed screw on the primary side had to be turned in or out more then 1 turn,it may be nessasary to split that amount with the secondary idle screw or throttle plate stop. Throttle plate openings when done should be within 1/2 turn of the adjustment screw between primary and secondary throttle plates.
 
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